WASHINGTON -- Camilo Sanvezzo scored his ninth goal of the season on a penalty kick in the second half, lifting the Vancouver Whitecaps to a 1-0 victory over D.C. United on Saturday night.

The Whitecaps' defense preserved just its second league shutout of the season in the victory, and its first since a 1-0 home victory against Toronto F.C. in the season opener on March 2.

Vancouver (7-5-4) has won three straight behind Sanvezzo, who has scored six goals in its last four league matches.

United (2-12-3) was shut out for the 10th time this season and resumed its losing form after snapping a club-record 13-match winless run with a 1-0 home win over San Jose last weekend.

Sanvezzo's goal came after Matt Watson got free on the left side and drew the penalty after colliding with D.C. goalkeeper Bill Hamid, who was trying to poke the ball away with an outstretched arm.

Replays showed that Hamid did touch the ball, but that he also crashed into Watson's legs afterward.

Sanvezzo blasted the resulting penalty kick straight down the middle and past Hamid, who guessed to his left.

Hamid made a pair of saves in the 64th minute to prevent Vancouver from doubling its lead, denying efforts from near the edge of the penalty from Jordan Harvey and then Russell Tiebert.

Dwayne De Rosario nearly scored for D.C. in the second minute when he volleyed a corner kick just wide of the right post. United then had a pair of chances five minutes later, when Brad Knighton saved Kyle Porter's close-range shot from the left and his defense deflected De Rosario's rebound effort over for a corner.

Vancouver's best chance of the half came in the 12th minute, when Teibert's low, close-range strike from the left rattled the near post.